Radar level gauge systems are currently in use in a variety of fields of application for accurate filling level determination. For determining the filling level of a product by means of a radar level gauge system, electromagnetic signals are transmitted and propagated, usually by means of an antenna, towards a surface of the product, where signals are reflected. The reflected signals are received by the radar level gauge system, and the distance between a reference position and the surface of the product is determined by comparing the transmitted signals with the reflected signals. Based on this distance, the filling level can be determined.
Most radar level gauge systems on the market today are either systems that determine the distance to the surface of the product contained in the tank based on the difference in time between transmission of a pulse and reception of its reflection at the surface of the product, or systems that determine the distance to the surface based on the phase difference between a transmitted frequency-modulated signal and its reflection at the surface. The latter type of systems are generally referred to as being of the FMCW (Frequency Modulated Continuous Wave) type. There are also radar level gauge systems that are a mix between the two types mentioned above.
In many applications, especially when the product in the tank is a fluid, such as a liquid or a gas, it may be important to prevent leakage at the radar level gauge system from the interior of the tank to the exterior of the tank. To this end, radar level gauge systems are typically provided with at least one process seal.
In case of failure of the seal(s) of a radar level gauge system, there will be a leakage of, potentially harmful, fluid from the tank to the surrounding atmosphere.
According to one approach for minimizing the risk and/or loss of product associated with the leakage, US 2006/0225499 discloses a sealing system comprising a primary seal, a secondary seal and a relief seal. In case of failure of the primary seal and the secondary seal, gas from the interior of the tank is allowed to leak out from the tank through the relief seal in such a way that an audible or aromatic annunciation is provided.
Although this approach provides an indication of leakage from the tank, there still appears to be room for improvement, in particular with regard to the ability to detect the leakage from a remote location and/or the reliability of the leakage detection.